diff --git a/paper-api/src/main/java/org/bukkit/generator/BlockPopulator.java b/paper-api/src/main/java/org/bukkit/generator/BlockPopulator.java
index fff9f9a144..a2e12ea3e1 100644
--- a/paper-api/src/main/java/org/bukkit/generator/BlockPopulator.java
+++ b/paper-api/src/main/java/org/bukkit/generator/BlockPopulator.java
@@ -8,13 +8,15 @@ import org.bukkit.World;
  * A block populator is responsible for generating a small area of blocks.
  * For example, generating glowstone inside the nether or generating dungeons full of treasure
  */
-public interface BlockPopulator {
+public abstract class BlockPopulator {
     /**
-     * Populates an area of blocks at or around the given chunk
+     * Populates an area of blocks at or around the given chunk.
+     *
+     * The chunks directly surrounding the specified chunk must already exist.
      *
      * @param world The world to generate in
      * @param random The random generator to use
      * @param chunk The chunk to generate for
      */
-    public void populate(World world, Random random, Chunk source);
+    public abstract void populate(World world, Random random, Chunk source);
 }
diff --git a/paper-api/src/main/java/org/bukkit/generator/ChunkGenerator.java b/paper-api/src/main/java/org/bukkit/generator/ChunkGenerator.java
index 1e98051aaf..4b30f85951 100644
--- a/paper-api/src/main/java/org/bukkit/generator/ChunkGenerator.java
+++ b/paper-api/src/main/java/org/bukkit/generator/ChunkGenerator.java
@@ -8,7 +8,7 @@ import org.bukkit.World;
  * A chunk generator is responsible for the initial shaping of an entire chunk.
  * For example, the nether chunk generator should shape netherrack and soulsand
  */
-public interface ChunkGenerator {
+public abstract class ChunkGenerator {
     /**
      * Shapes the chunk for the given coordinates.<br />
      * <br />
@@ -32,7 +32,7 @@ public interface ChunkGenerator {
      * @param z The Z-coordinate of the chunk
      * @return byte[] containing the types for each block created by this generator
      */
-    public byte[] generate(World world, Random random, int x, int z);
+    public abstract byte[] generate(World world, Random random, int x, int z);
 
     /**
      * Tests if the specified location is valid for a natural spawn position
@@ -42,7 +42,7 @@ public interface ChunkGenerator {
      * @param z Z-coordinate of the block to test
      * @return true if the location is valid, otherwise false
      */
-    public boolean canSpawn(World world, int x, int z);
+    public abstract boolean canSpawn(World world, int x, int z);
 
     /**
      * Gets a list of default {@link BlockPopulator}s to apply to a given world
@@ -50,5 +50,5 @@ public interface ChunkGenerator {
      * @param world World to apply to
      * @return List containing any amount of BlockPopulators
      */
-    public List<BlockPopulator> getDefaultPopulators(World world);
+    public abstract List<BlockPopulator> getDefaultPopulators(World world);
 }